A digital signature (not to be confused with a digital certificate) is an electronic signature that is used to authenticate the identity of a message sender or document signer, and usually to ensure that the original message/document content is unchanged (document integrity).

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Digital Signatures of XML, PDF and Office Documents on every platform

I'm trying to develop a website that performs digital signatures on client-side and then sent the signed document to the server-side. I want to do the signatures on client, due to the fact of not ...
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3answers
152 views

Is it ok to send user's private key away, even if protected with a SSL channel?

I'm developing a webserver that performs digital signatures of (xml, pdf and office) documents and then validates those signatures. My idea is: an user puts its SmartCard and through a PIN, he gets ...
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4answers
69 views

Is it ok to send user's private key away, even if protected with a SSL channel? [duplicate]

I'm developing a webserver that performs digital signatures of (xml, pdf and office) documents and then validates those signatures. My idea is: an user puts its SmartCard and through a PIN, he gets ...
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1answer
73 views

Digitally signed scripts as a way to thwart XSS

As a blanket approach to dealing with XSS attacks, rather than having to remember to escape user-generated code, is there a way to instruct the browser not to execute any script or script-function ...
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1answer
110 views

Reading older mails signed with a certificate that has meanwhile expired

A few years ago I have used S/MIME certs to sign (and encrypt) my mails. The reason for which I stopped signing was the following: My (class 2) cert was issued on Jan. 1st 2008 (just a sample). It ...
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1answer
62 views

How to modify a certificate using getTBSCertificate() method

I want to show that if I modify one bit or byte from a given X509 certificate the signature verification results false (because this modification results different hash value from the certificate). ...
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1answer
175 views

valid PDF signature without using hardware HSM or usb Token

I have a DMS system(alfresco) that needs to sign approx 50.000 valid signatures a year. The signing certificate needs to be acquired from one of the affiliated sub-CA's. So according to the Adobe CDS ...
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1answer
164 views

Internal code-signing certificate on Windows

I'm looking to improve defense-in-depth on a system, primarily by closing some holes in injected DLLs. Certain applications installed on the system cause helper DLLs (e.g. shell extensions, BHOs, ...
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3answers
1k views

inquiry about SHA1 with RSA for certificate signature

As you all know, plenty of X.509 Certificates use (PKCS#1 SHA1 with RSA encryption) as the Certificate Signature Algorithm for generating the signature of 2048 Bits long. We know that SHA1 hash ...
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0answers
137 views

How to check executable code signing signatures?

How can I see all code signing signatures an executable has? I know that requests for a tool are usually considered as opinion based, but I really can't find one and I don't expect many answers. ...
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1answer
146 views

RSA vs ECDSA for VANET Security

I am doing a project on Vehicular Ad-Hoc Network Security (VANET). The proposed scheme uses electronic signature as a means to authenticating the nodes. Most of the research papers I read suggested ...
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4answers
171 views

How to verify full USB drive's digital signature

There are various ways to verify the validity of a file, usually checking the MD5 checksum or OpenPGP signature. Is it possible to do the same for a full USB Drive? I'd like to be able send a USB ...
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127 views

Digital signatures and truly validating what was actually agreed to

I am developing an application and part of signing up requires a user to sign a contract agreement of using the service. I have been reading around the subject for a few days, and I am fairly happy ...
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3answers
404 views

How are private keys handled in an enterprise?

We would like to start using digital signatures and possibly encryption for e-mails in our company. My knowledge of public-key cryptography is entirely theoretical with no practical experience. In ...
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1answer
141 views

How online document signing services guarantee non-repudiation?

There is a number of services online like RightSignature or SignHub that will let you sign online legally binding documents. I understand how documents can be signed digitally and this can guarantee ...
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1answer
62 views

Proof of quantum safety of the Merkle signature scheme

The Wikipedia article about the Merkle signature scheme claims that it is very adjustable and resistant against quantum computing. What proof is there of this?
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1answer
80 views

Ideal cryptocurrency digital signature

What are the characteristics of the ideal digital signature for cryptocurrency transaction verification? The reason I ask is because this answer about bitcoin signatures describes a potential ...
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1answer
270 views

Signing session cookies

The Play Framework for Scala has support for signed session cookies. In the application configuration file is an "application secret" that is set as a secure random number when the application source ...
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7answers
466 views

Authencity of information displayed on an untrusted device

Suppose I have a (bluetooth/usb) device which needs to displays information on an external pc/phone. Is there a simple and effective method to garantuee that the information displayed hasn't been ...
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1answer
157 views

DSA Generates different signatures with the same data [closed]

I'm using the example given in msdn article about the DSACryptoServiceProvider Class. The problem is that I get a different signature each time I run the code. I tried OpenSSL and didn't get this ...
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6answers
215 views

Does an email signature increase security?

I'm using Thunderbird with Enigmail. It has both encrypt and sign options for sending PGP emails -- but why is an email signature needed? It just looks overkill to me! Alice and Bob can use PGP to ...
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3answers
261 views

Can a zero knowledge proof of voting be made using a trusted auth server (without client side crypto)?

Questions: Can one implement a secure voting system having all the features described below? e.g. without disclosing any individual's vote to the government server (or the third party), preserving ...
3
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3answers
331 views

Is there an attack that can modify ciphertext while still allowing it to be decrypted?

Is there any way an encrypted file using AES-256 could be modified without alerting the file owner, ie., so it can still be decrypted with the same key? I know that without an initialization vector ...
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2answers
111 views

Subdomain-only SSL security/availability

CAcert and StartSSL both only validate domains whose TLD is owned by the requester. I have a few subdomains that come from places like freeDNS that I would like to run an SSL-secured server on. Are ...
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4answers
296 views

Evil certificate authority in public-key-infrastructure

Alice goes to the certificate authority (CA) and registers her public key for signature verification. She gets a certificate for this from the CA. Bob requests Alice' public signature verification key ...
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1answer
103 views

What protection certificates would be required for an application that consists of setup, loading utility and main application?

Say we have an InnoSetup installer script, a native C++ QT files loading application and a .Net client application that we load/update each time and which is the main application. We load files via ...
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180 views

How to detect authenticity Of Client and Server Certificate?

How its possible to detect authenticity Of Client and Server Certificate. For example, If server A has certificate and someone C stolen its certificate and send it to B then How we decide that it's ...
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735 views

Digital Certificate “Signature and Fingerprint”

What's the difference between Digital certificate's signature and fingerprint (thumbprint) ? I know that Signature: The actual signature to verify that it came from the issuer. and Thumbprint ...
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100 views

How to sign and encrypt mails using firefox

There is an option under Tools>options>Advanced>Security Devices. How to use that to encrypt and digitally signed your emails.
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1answer
106 views

Using secp256k1 and ECDSA with IKE

I just tried using an IKE daemon and EC certificates. I used the secp256k1 curve for key generation. The daemon claims signature scheme ECDSA-256 not supported by private key Now I am wondering ...
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196 views

Implementing OAuth flow in JavaScript

I am making a custom auth flow for the application. It is inspired by OAuth 2.0. Dev sends user to an auth page on my domain, passing callback_url and api_id. I redirect user to callback_url, passing ...
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4answers
212 views

Is it possible to digitally sign information with a password?

I'm creating a cloud storage service and need to have the ability to provide reliable security for clients. In my previous question, I used a different schematic and said I would post a new question. ...
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0answers
106 views

Techniques for web-user communication across an untrusted server

I'm designing a web-based notification framework (i.e. a user can subscribe to updates from a service or another user) where communication between users is encrypted. User-to-user communication on ...
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1answer
289 views

The Hash header in GPG ASCII armor

When sending a signed message using GPG, it always includes a line that says Hash: SHA256 right at the top of my email. I was wondering if/why it's required, and if not, how I can remove it (in an ...
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1answer
306 views

Secure API access over SSL using oauth token

On the project that i'm currently working, we authenticate the clients by username and password. In this system each user has a key which is calculated from his password. However, we want to provide ...
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2answers
166 views

Can the client certificate authentication process treated as a user digitally signed the content(and then get verified on the server)?

The authentication was triggered by certain event (like approving button) on the form. In the process of client certificate authentication (in IIS), user was asked to use their PIN (private key) and ...
3
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1answer
141 views

How signature validation would be checked on server side?

Sorry, It may be possible that few things are repeated in my question. I have gone through some documentation/discussion signing an API request and twitter signature documentation As per the ...
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3answers
646 views

How can I prove that I wrote a certain blog post?

I would like to be able to prove that I wrote the article that resides at a given URL on someone else's blog. Is there a way that I can do this with public key cryptography? I know a bit about the ...
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3answers
7k views

How to prevent man-in-the-middle attacks beside of SSL?

I would like to discuss this scenario: There is a HTTPS service which responds with signed keys to an authenticated client. These signed keys can be used for another service to return very sensible ...
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2answers
448 views

Using a Common Private Key for Digital Signatures

I have a mobile application and a server. The mobile application communicates with the server through a web services framework via SSL. The mobile application allows customers to pay for ...
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1answer
378 views

GnuPG/KGpg Sign PGP Key - Sign User ID : What is the difference?

What is the difference between signing a user ID and a whole Key ? Which behavior is the best as to signing user IDs and Keys ? How and when to use "Local signatures" (non exportable) ? (I was told ...
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2answers
140 views

Deciding whether to sign someones key

How do i decide whether to sign someones PGP public key? I was looking at some contact pages and they have a request for people to sign their public key. How serious of a commitment is it to sign ...
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2answers
315 views

How do I securely identify a remote (self programmed embedded) device in PHP?

Is there a reliable way in PHP to identify a device that might be behind a Router (so the IP is not unique)? Background: I have several embedded devices (self programmed & adaptable) that contact ...
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2answers
74 views

Which signing strategy?

I have a device which should lock and unlock something after receiving a signed server response. So in the best case a loop would lock like this: User locks device User wants to unlock device User ...
3
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1answer
547 views

Can you make a digital signature using the receiver's public key?

My question is, can you make a digital signature using the receiver's public key and then have the receiver verify the signature using his private key? I always thought that in order to create a ...
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2answers
101 views

Are there any systems to mitigate the risk of losing a Signing Key?

I want to design a system that hinges on ECDSA. All messages are signed using the algorithm, and this is used to prevent spoofing. However, if a user were to somehow lose control of their key, they ...
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3answers
349 views

Why a self-signed digital certificate (X.509) cannot be altered?

I'm not experienced in code signing but I was thinking about this: as you know, there are various tools for self-signing digital certificate generation (as makecert from Windows or OpenSSL). Now, It ...
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2answers
117 views

Protection of online image file (ancient manuscript) [duplicate]

I am going to protect an image file (ancient manuscript) which will be available online for everyone to download. I want to protect the file in these situations: When it's on the server, I need to ...
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1answer
341 views

Advantages of using a Digital Signature Scheme (DSS) with Appendix instead of DSS giving Message Recovery

I've been looking at the EMV draft specification (pdf) for using Eliptic Curve Cryptography in payment cards instead of the currently used RSA. One thing I've noticed is that they've moved from using ...
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1answer
133 views

Licensing/selling digital certificate to another company

I recently stopped distributing my software, so I no longer use the digital certificate (AKA digital signature) I created for it. A couple of days ago, a large software company offered to buy the ...